Combined high and low pressure pump



July 8, 1930. w. BussMANN COMBINED HIGH AND LOW PRESSURE PUMP Filed Dee. 29, '1927 4 sheets-sheet 1 a v w WI Mmm@ HHIIIIIII 4 Sheets-Sheet 2 .UWE

' Filed Dec. J29; 1927 W. BUSSMANN COMBINED HIGH- AND LOW PRESSURE PUMP i IIIIIII July 8, 1930.

i' wwf/vrom f W12/kn un assmann y f fm JUY 8)' 1930- w. BUs'sMANN I COMBINED HIGH AND LOW PRESSURE PUMP Fil'ed peo. 29. 1927 4 Smets-sheet 3 July 8, 1930 Aw. BU'ssMANN COMBINED HIGH AND LCV-1 PRESSURE PUMP Fiied Deo. 29. "1927 4. sheets-sheet 4 Patented July 8, 1930 'UNITED STATES 'WILHELM Rossmann,

OF MUNICH, GERMANY COIMBINED HIGH AND LOW PRESSURE PUMP Application led December 29, 1927, Serial No. 243,424, and in Germany January 28, 1927.

The present invention relates to a coinbined higli and low pressure pump and has for an object to provide a device of thecharacter mentioned having automatic means for releasing the 1017iI pressure pump as soon as a' of the invention will be in part obvious and in part pointed out hereinafter.

In order lthat the invention and its mode of operation may be readily understood by those skilled in the. art, I have in the accompanying drawings, set out the possible embodiments of the invention.

In these drawings Figure 1 is a face elevation of the device on the low pressure pump side with the cover removed;

Figure 2 is a section taken through line III- III of Figure 1. v

Figure 3 is a face elevation of the device on the high pressure pump side showing portions in section;

Figure 4 isa diagrammatical representation of myinvention with the reversing device attachedthereto;

Figure 5 isfa lsection through the pump;

Figure 6 is a detail of a portion of the Pump;

Figure 7 illustrates the stopping device used in connection with my invention.

Figure 8 is a front yview of the operating valve;

Figure 9is a side view of the same; Figure 10 is a vertical section through said valve, and

Figure 11 is a horizontal section thereof. IThe low-pressure pump is an ordinary gear-pump, the high-pressure one has a barrel with radial bores. Thelow-pressure gearpump, with the two pinions 1 and 2 1n casing 3, delivers the liquid coming from the pipeline 4 through the connecting pipe 5. to the high-pressure pump and to the ringhlre chamber 6 arranged theres-bout, the liquid filling said high-pressure pump and the chamberv 6. But a part ofthe liquid flows through the valve 7 of the inside ring 8 into the main 9. Another part flows into the bores 11 after having lifted and passed the valves 10. When y the plungers 12 are outwardly moved, valves 10 are closed and pressure-Valves 13 opened.

The liquid then passes through the outlets 14 into the outside ring-chamber 15 flowing therefrom into main 9. A special device to return the plungers 12 against the eccentric 16 is not necessary, the plungers being always brought against the eccentric bythe pressure of the liquid entering the bores'.

' As soon as the pressure in' the main has attained a certain value and acts upon Valve "7 in such a Way, that the pressure developed" by the lgear-pump 1 and 2 does not suflice to lift this valve 7, the delivery of the highpressure pump alone is discharged through the outlets 14 and. the ring-space 15 into the -main.

. Whenpressure falls the valve 7 opens again and the gear-pump 1 and 2 takes part in the delivery to the main 9. With low pressurevalues, say between O and 52 lb. per'sq. in., a very fast filling and in this way a very fast raising of pressure is attained, for the entire delivery Q of the gear-pump is discharged into the main. This ,delivery is governed by the quantity of liquid entering into the ring-space 6, flowing through valve 7, and

by the quantity delivered by the plungerpump. As soon as the pressure has attained the value of 52 lb.- per 'sq.'in. a little increase of the delivery of the gear pump will suffice to cause a rapid increaseA of pressure, because the whole power developed by the plunger- -pump is only employed for raising the pressure of the liquid flowing at the pressure of .pinions-l7 and 18 of the gear-pump.' The inlet-port 19 of the gear-pump 1s arranged on the side and, opposite thereto, is the inletport 20 of the high-pressure pump. In the L,example illustrated on the 'drawing 1n Figs. 1 and 2 the low-pressure pump 1s arranged e the gear-pump. The drawings show the two r in front of the high-pressure pump and both umps are centrally mounted lwith respect to each other, the shaft 21 of the *plungermain 29.

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pump driving at the same time one of the two pinions. The motion of the plungers 22 of the high-pressure pump is performed by driving them against a ball-bearing 23. This ball-bearing is then mounted on a crank 24 of the shaft 2l. The delivery of the low-pressure pump is Vdischarged through the chamber 20 and it passes through the valves 25 to the barrel 26. The pressure then exerted upon the plungers 22 drives the latter against the ball-bearing 23 carried by the crank'24. lVhen the plungers are going down, the delivery will open valves 27 and it will ilow through these valves into the ring-space 28, from which the liquid will arrive to the main 29.

As long as aV determined high pressure, to be controlled, is not attained, the remaining ,portion of the liquid will `lift the check-valve 30 of the ring-space 20 and it will flow into the transverse chamber 31. From this chamber the li uid is then discharged into the ut if the pressure surpasses a. certain value, sov that the pressure of the delivery of the gear-pump would not be able to overcome the counter-pressure acting upon valve 30, the liquid will iiow to the plungerpump only and it will be discharged by the latter into the main. In this case the delivery of `the low-pressure pump will surpass the capacity of the plunger-pump. For this reason the arrangement of a valve to be fixed on the connecting pipe would be advisable (this valve has not been drawn on the drawing), the valve allowing the surplus to discharge into the oil-tank. Fig. 3 shows on section between A and B the high-pressure check-valve. The inlet-valves for the highpsressure pump are shown on section between and C, the high-pressure plungers on seci tion between C and D and finally the highpressure outlet valves on section between D and A..

From the connecting pipe 5 between the hiO-hand low-pressure pump a tube branches o which tube may be closed by the valvecone 33. This valve-cone is acted upon by the adjustable spring 34. From tube 32 a passage 35 leads to a reversing-device and a second assage 37 connects the casing 36 of the sprlng 34 to the reversing-device. This reversing-device consists of a sleeve, in which the double-plunger 39, 40 reciprocates, the two heads of this plunger being held together by rods. An extension 42 ot the rods bears on a spring-plate 43 acted on by an adjustable counter-spring 44. The casing 38 of the reversing-device is provided with an outlet-port 45 discharging into the oil-tank (the whole pump lying in oil). The casing of the reversing-device communicates through a passage 46 with the main 9, s'o that the pressure of the main acts on the rear-side of the plunger 39. lfvthe pressure in the main 9 surpasses the pressure exerted by spring 44, the two plunger heads 39 and 40 are shifted to cover port 35 and leave open ports 37 and 45. Further outlet-ports 47 are provided in the valvedisc for the purpose of admitting oil into the casing, when valve 33 is open.

As it will be understood from the diagram explaining the working of the pump, if the low-pressure pump force the liquid to` the high-pressure pump, the 'same pressure will to be found in the passages 32, 35, in the space between the double plunger 39, 40 of the reversing-valve v38, in the return-passage 37 and in the casing 36 at the rear of the valve. Valve 33 is completely balanced. If now the pressure-in the main 9 rises, say to 35 lb. per sq. in. and the spring 44 of the reversing-valve 38 is adjusted toy this very pressure, the double-plunger 39, 40 will overcome the pressure of spring 44 at any further increase of pressure. The double-plunger will recede, covering port 35, while ports 37 and 45 will at the same time be opened. .By this means valve 33, which was balanced before, will be relieved on the rear-side. It will open, so that in the connecting-'pipe 5 and in the passage 6 a decrease of pressure will immediately Jfollow, which decrease of pressure will cause valve 7 to close at once. Valve 33, which is now constantly relieved on its rear-side, will not allow any pressure higher than 28 lb. per sq. in., spring 34 having been adjusted to this very pressure. The surplus of delivery will now lift valve-cone 33 in the valve-disc and it will discharge through ports 47. However, a large quantity of liquid will still be delivered tothe high pressure pump. But, ais at rising pressure, a relative small quantity -of'liquid is required for causing a further increase of pressure, the pump will not be able to work with the added quantity of liquid delivered to the high-pressure pump. Thus, 1n order to avoid losses due to inner-friction which would occur, when the pump would movement of the plungers may be adjusted` in such a way, that they are prevented from goin all the waytback, but more or less play may e left between the eccentric and the adjacent portions of the plunger accordingly to the position of the cam-disc, against which the plungers with their stops 49 strike.- In this way a reduction ofthe stroke is reached or, 1n other words, the stroke-volume is made smaller.

An example of this arrangement, diagrammatically shown Fig. 4, is reproduced in l Figs. to 11. Figs. 5 Vto 7 represent the stroke-altering device, while Figs. 8 to 11 show the operating valve.

The pump-cover 50 carried a shaft 51 having side-arms 52. These arms 52 engage tw'o extensions 53 of the cam-disc 48, which cam-disc having on the opposite side the inclined-planes, above mentioned. Plungers 22 have at their lower-ends 57 right-angled slots for these inclined lanes of the cam-disc 48. Dependent upon t e position of this camdisc, the upper- "xtensions 54 of the plungers 22 come earlier or later to strike it. In this way the moving down of the plungersis controlled. If the said extensions come earlier to strike the cam,the stroke-volume' is rel duced. The latter is increased, if the extensions come later to touch the cam. This shifting of the cam-disc may be either mechanically performed in connection with valve 38, that is to say, with the operating valve 36, or by hand. To this purpose cam-disc 48 is provided with the abve extensions 53, which pass throughslots 55 of the lower-cover 56, I

prising a low pressure pump and a high pre'sthe cover being at the same time the bearing for the shaft 21. The side-arms 52 of the shaft 51 engage the spaces subslsting` between two extensions 53. If shaft 51 is rotating, it will turn the cam-disc. I In this way the extensions .54 of the plungers 22 would earlier or llater strike the cam-disc 48. The operating-valve 36 in Figs. 8-11 has a casing 58, which is piped to the connecting-tube between highand low-pressure pump by means of a screwed spcket59. The operating-valve has a valve-cone 60, acted on by springv 61,

which can be adjusted by screw 62. The

change-over passage 63 connects the passage between highand low-pressure pump 20 with the distribution-passage 64 arranged in the casing 65, placed sidewards. The doublepl'unger 66, 67 moves in the distribution-passage, the lone end of said plunger contacting with the spring-plate 68. The adjustable spring 69 acts by -means of a nut 70 on the' spring-plate, pushing this end of the doubleplun er into one of the end-positions. Passage 1 branches off from the main and leads to the opposite end of the double-plunger, so

. that the pressure, which acts on the plunger,

can only shift the same. The spring is then drawn together. Three passages'72, 63 and 7 3 lead to passage 64. If the spring-pressure does overcome the pressure transmitted from the main, passages 63 and 73 will communicate with each other. Frontand rear-end o'f valve 60 are acted on by the same pressurevalue. The valve will thereforelbe balanced.

But if the pressure deriving from the main does overcome the counter pressure exerted by spring 69, the plunger will be shifted.

In this case passages 72 and 73 will communicate with each other, so that the rear-side of the valve 60 will-be relieved and the valve itself be caused to open.- The liquid will now ilow through ports 74. A vacuum will -rise in the pipe-lines between the low-pressure pump and the main 9,' the vacuum causing valve 30 to close. Double-plunger 66, 67 will still retain its position and the surplus of the delivery of the vlow-pressure pump will flow back into the oil tank through .the lifted valve-cone 60 and the ports 74.

I claim:

'1. A device of the character described comprising a low pressure pump, a high pressure pump receiving the delivery from the low pressure pump, the high pressure pump being providedwithA a first system of passageways for the admission to said highfpressure pump of the delivery from the low pressure pump and with a secondr system of passageways for the delivery of said high pressure pump, means of communication between the two systems of passageways said high pressure pump, and a valve for controlling the communication between said systems of passageways.

2. A device of the character' described comsure pump receiving the delivery from the low pressurepump, the high pressure pump being provided with a first system of passageways'. for the admission to said high pressure pump of the delivery from the low pressure pump and with a second system of passageways for the delivery of said high pressure pump,

4means of communication between the two systems of passageways in said high pressure pump, a valve for controlling the communication between said system ofpassageways, and means communicating) with the .high pressure pump and the low pressure pump for limiting and controlling the value of pressure between said pumps when a pre-l determlned pressure is obtained.

3. A device of the character described com'-l los prising a low pressure-pump, a high pressure pump receiving the delivery from the low pressure pump, the highpressure pump being rovided'with a first system of passageways or theadmission to said high pressure pump of the delivery from the low pressure pump and with a secondV system of passageways for the delivery of the high pressure pump, means of communication between the two systems of lpassageways in the high pressure pump, a

the valve operating under diierent pressures to open and-close certain of said ports.

4.' A device of the character described comprising a low pressure pump,.a high pressure pump receiving the delivery from the low pressure pump, the high pressure pump being provided with a rst system of passageways `for the admission of said high pressure pump of the delivery fromthe low pressure pump and with a second system of passageways for the delivery of said -high pressure pump,

-means of communication between the two high pressure pump, control means of comsystems of passageways in said high pressure pump, a valve for controlling communication between said system of passageways, and means communicating with the high pressure pump and the low pressure pump for limitl'ng and controlling the value of pressure between said pumps when a prev determined pressure is obtained, said means including a piston valve having series of cooperating ports, a spring holding said valve in normal position, saidvalve adapted to open and close certain of said ports when subjected to a pressure overcoming the counterpressure of the spring.

-5. A device of the character described comprising a low 'pressure pump, a high pressure pump receiving the delivery from the low pressure pump, said high pressure pump consisting of a body, a plurality of pistons radially, mounted in said body, means to actuate said pistons, and being provided with a first system of passageways for the admission to said high pressure pump of the delivery froml the low pressure pump and with a second system of passageways for the delivery of said high pressure pump, controlled means of communication between the two systemsv of passageways in said high pressure pump, and means associated with the pistons of the high pressure pump for regulating the stroke of the pistons.

6. g A device of the character described com` prising a low pressure pump, a high pressure pump receiving the delivery from the low pressure pump said high ressure pump consisting of a body,a plura ity of pistonsradially mounted in said body, means to actuate said pistons and being provided with a first system of passageways for the,admission to said high pressure pump of the delivery from the low pressure pump and with a second system of passageways for the delivery 0f said municationbetween the two systems of passageways in said high pressure pump, and means associated with the pistons of the high pressure pump for regulating the stroke of the pistons, said means consisting of an ad instable eccentrcally mounted disk provided with a plurality of adjacent inclined surfaces t engageable with said pistons.

- In testimony whereof, I have signed my name to this specification.

WILHELM BUSSMANN. 

